What Causes Persistent Bump On Labia Minora?

I have this bump that keeps appearing on my labia minora, it only appears after I ve worked out or I ve sweat a lot and haven t been able to get into the shower yet... it itches and then once I shower it s fine and doesn t itch anymore but it s like it never really leaves? I can always see it... it just chooses when it wants to act up...